1. Field of the Invention
The present invention relates to a magnetic encoder using a magnetoresistive sensor which reduces a demagnetization field and which has a narrow width.
2. Description of the Prior Art
A magnetic encoder is used as a technology for measuring the position of a driver and the rotation number thereof by using a magnetoresistive sensor and the like. As a magnetoresistive film used for a magnetic sensor part, there are known a magnetic thin film having an anisotropic magnetoresistance, a so-called giant magnetoresistive film which is a multilayered film formed by stacking ferromagnetic metal layers with a nonmagnetic metal layer interposed between each pair thereof, a tunneling magnetoresistive film and the like. There is a spin-valve film as a technology similar to that used for a reproduction sensor of a magnetic head, and it is known as technology with which a giant magnetoresistance is obtained with high sensitivity.
Patent Document 1: U.S. Pat. No. 5,408,377
Patent Document 2: JP Patent No. 3017061
Patent Document 3: JP Patent Publication (Kokai) No. 2003-106866 A
Patent Document 4: JP Patent Publication (Kokai) No. 2006-023179 A